Program Operations Manual System (POMS)

The number of days of care charged to a beneficiary for inpatient hospital services
is always in units of full days. A day begins at midnight and ends 24 hours later.
The midnight-to-midnight method is used in reporting days of care for beneficiaries,
even if the hospital uses a different definition of day for statistical or other purposes.

A part of a day, including the day of discharge or death, or a day on which a patient
begins a leave of absence, is not counted as a day. (Charges for ancillary services
on the day of discharge are covered under the reimbursement formula.) if admission
and discharge or death occur on the same day, the day is considered a day of admission
and counts as one inpatient day.